Introduce limit to number of registered runners [RUN ALL RSPEC] [RUN AS-IF-FOSS]

app/models/ci/runner_namespace.rb

@@ -3,6 +3,11 @@
 module Ci
   class RunnerNamespace < ApplicationRecord
     extend Gitlab::Ci::Model
+    include Limitable
+
+    self.limit_name = 'ci_registered_group_runners'
+    self.limit_scope = :group
+    self.limit_feature_flag = :ci_runner_limits
 
     belongs_to :runner, inverse_of: :runner_namespaces
     belongs_to :namespace, inverse_of: :runner_namespaces, class_name: '::Namespace'

app/models/ci/runner_project.rb

@@ -3,6 +3,11 @@
 module Ci
   class RunnerProject < ApplicationRecord
     extend Gitlab::Ci::Model
+    include Limitable
+
+    self.limit_name = 'ci_registered_project_runners'
+    self.limit_scope = :project
+    self.limit_feature_flag = :ci_runner_limits
 
     belongs_to :runner, inverse_of: :runner_projects
     belongs_to :project, inverse_of: :runner_projects

app/models/concerns/limitable.rb

@@ -7,6 +7,7 @@ module Limitable
   included do
     class_attribute :limit_scope
     class_attribute :limit_name
+    class_attribute :limit_feature_flag
     self.limit_name = self.name.demodulize.tableize
 
     validate :validate_plan_limit_not_exceeded, on: :create
@@ -25,6 +26,7 @@ module Limitable
   def validate_scoped_plan_limit_not_exceeded
     scope_relation = self.public_send(limit_scope) # rubocop:disable GitlabSecurity/PublicSend
     return unless scope_relation
+    return if limit_feature_flag && ::Feature.disabled?(limit_feature_flag, scope_relation, default_enabled: :yaml)
 
     relation = self.class.where(limit_scope => scope_relation)
     limits = scope_relation.actual_limits

changelogs/unreleased/pedropombeiro-321368-limit-number-of-runners.yml

+---
+title: Introduce limit to number of registered runners
+merge_request: 60157
+author:
+type: added

config/feature_flags/development/ci_runner_limits.yml

+---
+name: ci_runner_limits
+introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/60157
+rollout_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/329438
+milestone: '13.12'
+type: development
+group: group::runner
+default_enabled: false

db/migrate/20210423155059_add_runner_registration_to_plan_limits.rb

+# frozen_string_literal: true
+
+class AddRunnerRegistrationToPlanLimits < ActiveRecord::Migration[6.0]
+  def change
+    add_column(:plan_limits, :ci_registered_group_runners, :integer, default: 1000, null: false)
+    add_column(:plan_limits, :ci_registered_project_runners, :integer, default: 1000, null: false)
+  end
+end

db/migrate/20210423164702_insert_runner_registration_plan_limits.rb

+# frozen_string_literal: true
+
+class InsertRunnerRegistrationPlanLimits < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  def up
+    create_or_update_plan_limit('ci_registered_group_runners', 'free', 50)
+    create_or_update_plan_limit('ci_registered_group_runners', 'bronze', 1000)
+    create_or_update_plan_limit('ci_registered_group_runners', 'silver', 1000)
+    create_or_update_plan_limit('ci_registered_group_runners', 'gold', 1000)
+
+    create_or_update_plan_limit('ci_registered_project_runners', 'free', 50)
+    create_or_update_plan_limit('ci_registered_project_runners', 'bronze', 1000)
+    create_or_update_plan_limit('ci_registered_project_runners', 'silver', 1000)
+    create_or_update_plan_limit('ci_registered_project_runners', 'gold', 1000)
+  end
+
+  def down
+    %w[group project].each do |scope|
+      create_or_update_plan_limit("ci_registered_#{scope}_runners", 'free', 1000)
+      create_or_update_plan_limit("ci_registered_#{scope}_runners", 'bronze', 1000)
+      create_or_update_plan_limit("ci_registered_#{scope}_runners", 'silver', 1000)
+      create_or_update_plan_limit("ci_registered_#{scope}_runners", 'gold', 1000)
+    end
+  end
+end

db/schema_migrations/20210423155059

+c582b7dda33492e122725001200aeb470cbf4458f247728a3b2102e325c97193
\ No newline at end of file

db/schema_migrations/20210423164702

+b5e34f7827edcdf81c66250353cddc3481e39c693f983df610b8ed20c58cb65b
\ No newline at end of file

db/structure.sql

@@ -16025,7 +16025,9 @@ CREATE TABLE plan_limits (
     daily_invites integer DEFAULT 0 NOT NULL,
     rubygems_max_file_size bigint DEFAULT '3221225472'::bigint NOT NULL,
     terraform_module_max_file_size bigint DEFAULT 1073741824 NOT NULL,
-    helm_max_file_size bigint DEFAULT 5242880 NOT NULL
+    helm_max_file_size bigint DEFAULT 5242880 NOT NULL,
+    ci_registered_group_runners integer DEFAULT 1000 NOT NULL,
+    ci_registered_project_runners integer DEFAULT 1000 NOT NULL
 );
 
 CREATE SEQUENCE plan_limits_id_seq

doc/administration/instance_limits.md

@@ -435,6 +435,32 @@ installation, run the following in the [GitLab Rails console](operations/rails_c
 Plan.default.actual_limits.update!(ci_max_artifact_size_junit: 10)
 ```
 
+### Number of registered runners per scope
+
+> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/321368) in GitLab 13.12.
+
+The total number of registered runners is limited at the group and project
+levels. Each time a new runner is registered, GitLab checks these limits. A
+runner's registration fails if it exceeds the limit for the scope determined by
+the runner registration token.
+
+- GitLab SaaS subscribers have different limits defined per plan, affecting all projects using that plan.
+- Self-managed GitLab Premium and Ultimate limits are defined by a default plan that affects all projects:
+
+    | Runner scope                                | Default value |
+    |---------------------------------------------|---------------|
+    | `ci_registered_group_runners`               | 1000          |
+    | `ci_registered_project_runners`             | 1000          |
+
+    To update these limits, run the following in the
+    [GitLab Rails console](operations/rails_console.md#starting-a-rails-console-session):
+
+    ```ruby
+    # Use ci_registered_group_runners or ci_registered_project_runners
+    # depending on desired scope
+    Plan.default.actual_limits.update!(ci_registered_project_runners: 100)
+    ```
+
 ## Instance monitoring and metrics
 
 ### Incident Management inbound alert limits

doc/user/gitlab_com/index.md

@@ -98,11 +98,12 @@ Any settings or feature limits not listed here are using the defaults listed in
 | Artifacts maximum size (compressed) | 1G                | 100M          |
 | Artifacts [expiry time](../../ci/yaml/README.md#artifactsexpire_in)   | From June 22, 2020, deleted after 30 days unless otherwise specified (artifacts created before that date have no expiry).           | deleted after 30 days unless otherwise specified    |
 | Scheduled Pipeline Cron | `*/5 * * * *` | `3-59/10 * * * *` |
-| [Max jobs in active pipelines](../../administration/instance_limits.md#number-of-jobs-in-active-pipelines) | `500` for Free tier, unlimited otherwise | Unlimited
+| [Max jobs in active pipelines](../../administration/instance_limits.md#number-of-jobs-in-active-pipelines) | `500` for Free tier, unlimited otherwise | Unlimited |
 | [Max CI/CD subscriptions to a project](../../administration/instance_limits.md#number-of-cicd-subscriptions-to-a-project) | `2` | Unlimited |
 | [Max pipeline schedules in projects](../../administration/instance_limits.md#number-of-pipeline-schedules) | `10` for Free tier, `50` for all paid tiers | Unlimited |
 | [Scheduled Job Archival](../../user/admin_area/settings/continuous_integration.md#archive-jobs) | 3 months | Never |
 | Max test cases per [unit test report](../../ci/unit_test_reports.md) | `500_000` | Unlimited |
+| [Max registered runners](../../administration/instance_limits.md#number-of-registered-runners-per-scope) | `50` per-project and per-group for Free tier,<br/>`1_000` per-group for all paid tiers / `1_000` per-project for all paid tiers | `1_000` per-group / `1_000` per-project |
 
 ## Account and limit settings
 

spec/controllers/groups/runners_controller_spec.rb

@@ -302,6 +302,9 @@ RSpec.describe Groups::RunnersController do
 
     context 'when user is not an owner' do
       before do
+        # Disable limit checking
+        allow(runner).to receive(:runner_scope).and_return(nil)
+
         group.add_maintainer(user)
       end
 

spec/factories/ci/runner_namespaces.rb

+# frozen_string_literal: true
+
+FactoryBot.define do
+  factory :ci_runner_namespace, class: 'Ci::RunnerNamespace' do
+    runner factory: [:ci_runner, :group]
+    group
+  end
+end

spec/models/ci/runner_namespace_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Ci::RunnerNamespace do
+  it_behaves_like 'includes Limitable concern' do
+    subject { build(:ci_runner_namespace, group: create(:group, :nested), runner: create(:ci_runner, :group)) }
+  end
+end

spec/models/ci/runner_project_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Ci::RunnerProject do
+  it_behaves_like 'includes Limitable concern' do
+    subject { build(:ci_runner_project, project: create(:project), runner: create(:ci_runner, :project)) }
+  end
+end

spec/requests/api/ci/runner/runners_post_spec.rb

@@ -91,6 +91,21 @@ RSpec.describe API::Ci::Runner, :clean_gitlab_redis_shared_state do
           it_behaves_like 'not executing any extra queries for the application context' do
             let(:subject_proc) { proc { request } }
           end
+
+          context 'when it exceeds the application limits' do
+            before do
+              create(:ci_runner, runner_type: :project_type, projects: [project])
+              create(:plan_limits, :default_plan, ci_registered_project_runners: 1)
+            end
+
+            it 'does not create runner' do
+              request
+
+              expect(response).to have_gitlab_http_status(:bad_request)
+              expect(json_response['message']).to include('runner_projects' => ['is invalid'])
+              expect(project.runners.reload.size).to eq(1)
+            end
+          end
         end
 
         context 'when group token is used' do
@@ -117,6 +132,21 @@ RSpec.describe API::Ci::Runner, :clean_gitlab_redis_shared_state do
           it_behaves_like 'not executing any extra queries for the application context' do
             let(:subject_proc) { proc { request } }
           end
+
+          context 'when it exceeds the application limits' do
+            before do
+              create(:ci_runner, runner_type: :group_type, groups: [group])
+              create(:plan_limits, :default_plan, ci_registered_group_runners: 1)
+            end
+
+            it 'does not create runner' do
+              request
+
+              expect(response).to have_gitlab_http_status(:bad_request)
+              expect(json_response['message']).to include('runner_namespaces' => ['is invalid'])
+              expect(group.runners.reload.size).to eq(1)
+            end
+          end
         end
       end
 

spec/requests/api/ci/runners_spec.rb

@@ -999,6 +999,19 @@ RSpec.describe API::Ci::Runners do
             end.to change { project.runners.count }.by(+1)
             expect(response).to have_gitlab_http_status(:created)
           end
+
+          context 'when it exceeds the application limits' do
+            before do
+              create(:plan_limits, :default_plan, ci_registered_project_runners: 1)
+            end
+
+            it 'does not enable specific runner' do
+              expect do
+                post api("/projects/#{project.id}/runners", admin), params: { runner_id: new_project_runner.id }
+              end.not_to change { project.runners.count }
+              expect(response).to have_gitlab_http_status(:bad_request)
+            end
+          end
         end
 
         it 'enables a instance type runner' do